QTreeWidget indexAt() doesn't work

[Bonnie]

Are you filtering the events from a itemWidget?
The pos from the mouse events is in the coordinate system of that itemWidget, not the treeWidget.
You can:

1. map the pos from itemWidget to treeWidget's viewport

QPoint pos = itemWidget->mapTo(treeWidget->viewport(), e->pos());

2. map the global pos to treeWidget's viewport

QPoint pos = treeWidget->viewport()->mapFromGlobal(e->globalPos());

P.S.setMouseTracking(true) does not affect the pos value. It only makes you receiving mouse move events from the widget even no buttons are pressed.

[FluentCoding]

Ouch, I'm filtering them from the window because I want to check if I click away from a QTableWidget globally. I'll try it out :D Thanks, @Bonnie!

[Bonnie]

@FluentCoding Hmm..if you are not filtering from treeWidget's child widgets, then the first option need some change...

[FluentCoding]

Which? But I could use the second method as well?

[SGaist]

What about the focusOutEvent ?

[Bonnie]

@FluentCoding Yes, the second is ok to use. It maps from global pos, so nothing to do with their child/parent relation.
The first one must map from child to a parent (recursively).
If you'are filtering the window, and the window is a parent of treeWidget, then it should be changed to

QPoint pos = treeWidget->viewport()->mapFrom(window, e->pos());

[FluentCoding]

@Bonnie Thank you for the solution! Both work but have the same problem - when I'm scrolling a bit down in my QTableWidget, then I have the problem that the item gets shown as valid although I don't click on the widget.

My Code:

bool MainWindow::eventFilter(QObject* obj, QEvent* event) {
    if (event->type() == QEvent::MouseButtonPress) {
        QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);

        QPoint pos = ui->treeWidget->viewport()->mapFromGlobal(mouseEvent->globalPos());
        QModelIndex index = ui->treeWidget->indexAt(pos);

        if (!index.isValid() && ui->treeWidget->selectedItems().count() == 1) {
            ui->treeWidget->clearSelection();
        }
    }
}

[FluentCoding]

@SGaist Didn't try it out yet, but I don't think that it would be better than the eventFilter()-solution :/

[Bonnie]

@FluentCoding Yes, the viewport is partly invisible, so the index got from indexAt may be not visible.
That's what you need to do when you map the pos not from treeWidget's child.
You need to see whether it is contained in treeWidget's rect, whether it is on the scrollbar or not...
I think it's a bit complicated, maybe you should try what @SGaist suggest, use the focusOutEvent.
This is what I think to solve the problem (but not usable when you have set any itemWidget)

QPoint pos = ui->treeWidget->mapFromGlobal(e->globalPos());  //map pos to treeWidget
if(ui->treeWidget->rect().contains(pos) &&  //pos is inside of treeWidget
    ui->treeWidget->childAt(pos) == ui->treeWidget->viewport() &&  //pos is not on scrollbars
    ui->treeWidget->indexAt(ui->treeWidget->viewport()->mapFromParent(pos)).isValid()) {  //get index from viewport, maybe you don't need this line
    //valid index
} else {
    //invalid index
}

[FluentCoding]

@Bonnie Thank you so much, Bonnie! It worked!